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Update on H 4l analysis A. Khodinov * and K. Assamagan ** * State University of New York at Stony Brook ** Brookhaven National Laboratory

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Data set (signal only) Z (*) e + e - Z (*) + - h ZZ (*) m h = 130 GeV h 4e h 4 h 2e2

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Framework details Number of Events 100.000 GeneratorPythia 6.217 (6.5.0) no filters Fully simulated with ATLSIM (6.5.0) VDC dataset simul_000033 geometry leveldc1 ( ) Reconstructed withATHENA (7.0.2 and 7.5.0) Job Options fileRecExCommon_jobOptions.txt Additional MC TruthSpcl_MC (F.Paige and I.Hinchliffe)

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Kinematical cuts as in TDR 1.e 1 + e 2 - or + - with p T >20 GeV (leading pair) e 3 + e 4 - or + - with p T >7 GeV (following pair) 2. Calculate invariant Z mass GeV or ( 6 GeV) m 12 = m Z 15 GeV or ( 6 GeV) GeV m 34 > 20 GeV

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Additional requirements (Our own) TRD + combinatorial treatment Instead of taking just the 2 hardest leptons as the leading pair, we look though all the possible 4 lepton combinations for the leading and following pairs but retain the combination where the leading pair is best reconstructed (we do not require hardest p T s): e 1 + e 2 - or + - with p T >20 GeV min(M z - M ld )

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Z-mass constraint Assuming the leading lepton pair come from an on-shell Z of mass m Z, rescale 4-momentums of the 2 leading leptons so that: p pm 0 /m ll Where m ll is the measured (reconstructed) invariant mass of the 2 leading leptons Do this before reconstructing the H mass To find m 0, on event by event basis we convolute detector resolution with the Breit-Wigner shape for Z: m 0 = max ( Gaussian(m ll, 0 ) * BW(m Z, Z ) ) where 0 is the detector resolution (by fitting m ll without the mass constraint )

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Leading M ll cut = Mz+-6 GeV Mass constraint applied 2.7 Norm ECAL factor =1/0.9845 mean 129.9 mean 129.9 mean 129.9 mean 130.2 h4h4 h 4e h 2e2 7.0.2 + FORTRAN (PAW)

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single muon reconstruction Fortran 7.0.2 AOD 7.5.0

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AOD 7.5.0 No mass constraint! Muid Combined Leading M ll cut = Mz+-6 GeV h4h4

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Summary and plans Work on the example of analysis h l using AOD. Our old-fashioned fortran analysis is used as the pattern. we are awaiting for STACO (MuonBox+XKalman) to implement into the h analysis. h 4e and h 2e2 will be added to AOD Analysis

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